Guess I just can't no satisfaction.. (or in this case response...)
This was the same issue I ran into over the weekend
( Please refer to :http://portal.smartertools.com/community/a2738/server-load.aspx )
We are running 64bit server. It was NOT IIS that spinning out .. but SM service itself.
It occurred on Sunday.. without any 'load' or hardly any traffic (you can read the post).
I was looking for a memory setting to control how much it used.. because it can kept climbing.
It spun out twice.. but hasn't repeated since then (of course it is only Weds. :)